The Orbit of a Comet Can Be Changed Significantly by Each

The orbit of a comet can be changed significantly by each of the following events except oneEXCEPT ONE.Which is the exception?

A) The comet has a collision with another body in the Kuiper belt.
B) The comet passes close to a major planet.
C) The comet is influenced by a number of smaller bodies (planets, asteroids, etc.) , which it passes while in the inner solar system.
D) As it nears the Sun, the blast of the material streaming away to form its tails can change its direction.